package com.corner.utils.imageloader;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Handler;
import android.text.TextUtils;
import android.widget.ImageView;

import com.corner.R;
import com.corner.app.GlobalParams;
import com.corner.utils.LogUtil;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Collections;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ImageLoader {

    public static final int FILE = 1;
    public static final int URL = 2;
    public static ImageLoader imageLoader;
    // 当进入listview时默认的图片，可换成你自己的默认图片
    final int stub_id = R.drawable.common_loading_img;
    MemoryCache memoryCache = MemoryCache.getInstance();
    FileCache fileCache;
    Context context;
    ExecutorService executorService;
    Handler handler = new Handler();//handler to display images in UI thread
    private Map<ImageView, String> imageViews = Collections.synchronizedMap(new WeakHashMap<ImageView, String>());

    private ImageLoader(Context context) {
        this.context = context;
        fileCache = new FileCache(context);
        executorService = Executors.newFixedThreadPool(5);
    }

    public static ImageLoader getInstance(Context context) {
        if (imageLoader == null) {
            return new ImageLoader(context);
        }
        return imageLoader;
    }

    public void DisplayImage(String urlOrUrl, int type, ImageView imageView) {
        imageViews.put(imageView, urlOrUrl);
        // 先从内存缓存中查找
        Bitmap bitmap = memoryCache.get(urlOrUrl);
        if (bitmap != null)
            imageView.setImageBitmap(bitmap);
        else {
            // 若没有的话则开启新线程加载图片
            queuePhoto(urlOrUrl, type, imageView);
            imageView.setImageResource(stub_id);
        }
    }

    private void queuePhoto(String urlOrPath, int type, ImageView imageView) {
        PhotoToLoad p = new PhotoToLoad(urlOrPath, type, imageView);
        executorService.submit(new PhotosLoader(p));
    }

    public Bitmap getBitmap(String url) {
        if (TextUtils.isEmpty(url)) {
            return null;
        }
        File f = fileCache.getFile(url);
        /**
         * 先从文件缓存中查找是否有
         */
        //from SD cache
        Bitmap b = decodeFile(f);
        if (b != null)
            return b;
        /**
         *  最后从指定的url中下载图片
         */
        //from web
        try {
            Bitmap bitmap = null;
            URL imageUrl = new URL(url);
            HttpURLConnection conn = (HttpURLConnection) imageUrl.openConnection();
            conn.setConnectTimeout(30000);
            conn.setReadTimeout(30000);
            conn.setInstanceFollowRedirects(true);
            InputStream is = conn.getInputStream();
            OutputStream os = new FileOutputStream(f);
            Utils.CopyStream(is, os);
            os.close();
            conn.disconnect();
            bitmap = decodeFile(f);
            return bitmap;
        } catch (Throwable ex) {
            ex.printStackTrace();
            LogUtil.e("getBitmap");

            if (ex instanceof OutOfMemoryError) {
                memoryCache.clear();
                return getBitmap(url);
            }
            return null;
        }
    }

    /**
     * decode这个图片并且按比例缩放以减少内存消耗，虚拟机对每张图片的缓存大小也是有限制的
     */
    //decodes image and scales it to reduce memory consumption
    private Bitmap decodeFile(File f) {
        try {
            //decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            FileInputStream stream1 = new FileInputStream(f);
            BitmapFactory.decodeStream(stream1, null, o);
            stream1.close();

            //Find the correct scale value. It should be the power of 2.
            final int REQUIRED_SIZE = GlobalParams.screenWidth;
            int width_tmp = o.outWidth, height_tmp = o.outHeight;
            int scale = 1;
            while (true) {
                if (width_tmp / 2 < REQUIRED_SIZE || height_tmp / 2 < REQUIRED_SIZE)
                    break;
                width_tmp /= 2;
                height_tmp /= 2;
                scale *= 2;
            }
            scale = scale < 2 ? 2 : scale;
            //decode with inSampleSize
            BitmapFactory.Options o2 = new BitmapFactory.Options();
            o2.inDensity = context.getResources().getDisplayMetrics().densityDpi;
            o2.inSampleSize = scale;
            o2.inPreferredConfig = Bitmap.Config.RGB_565;
            FileInputStream stream2 = new FileInputStream(f);
            Bitmap bitmap = BitmapFactory.decodeStream(stream2, null, o2);
            stream2.close();
            return bitmap;
        } catch (FileNotFoundException e) {
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 防止图片错位
     *
     * @param photoToLoad
     * @return
     */
    boolean imageViewReused(PhotoToLoad photoToLoad) {
        String tag = imageViews.get(photoToLoad.imageView);
        return tag == null || !tag.equals(photoToLoad.url);
    }

    public void clearCache() {
        memoryCache.clear();
        fileCache.clear();
    }

    //Task for the queue
    private class PhotoToLoad {
        public String url;
        public ImageView imageView;
        public int type;

        public PhotoToLoad(String urlOrPath, int t, ImageView i) {
            url = urlOrPath;
            type = t;
            imageView = i;
        }
    }

    class PhotosLoader implements Runnable {
        PhotoToLoad photoToLoad;

        PhotosLoader(PhotoToLoad photoToLoad) {
            this.photoToLoad = photoToLoad;
        }

        @Override
        public void run() {
            try {
                if (imageViewReused(photoToLoad))
                    return;
                Bitmap bmp;
                if (photoToLoad.type == FILE) {
                    bmp = decodeFile(new File(photoToLoad.url));
                } else {
                    bmp = getBitmap(photoToLoad.url);
                }
                memoryCache.put(photoToLoad.url, bmp);
                if (imageViewReused(photoToLoad))
                    return;
                BitmapDisplayer bd = new BitmapDisplayer(bmp, photoToLoad);
                handler.post(bd);
            } catch (Throwable th) {
                th.printStackTrace();
                LogUtil.e("PhotosLoader");
            }
        }
    }

    /**
     * 用于在UI线程中更新界面
     */
    //Used to display bitmap in the UI thread
    class BitmapDisplayer implements Runnable {
        Bitmap bitmap;
        PhotoToLoad photoToLoad;

        public BitmapDisplayer(Bitmap b, PhotoToLoad p) {
            bitmap = b;
            photoToLoad = p;
        }

        public void run() {
            if (imageViewReused(photoToLoad))
                return;
            if (bitmap != null)
                photoToLoad.imageView.setImageBitmap(bitmap);
            else
                photoToLoad.imageView.setImageResource(stub_id);
        }
    }

}
